EP0006680B1 - Apparatus with dielectric gas mixtures in substantially uniform field - Google Patents

Apparatus with dielectric gas mixtures in substantially uniform field Download PDF

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Publication number
EP0006680B1
EP0006680B1 EP79300804A EP79300804A EP0006680B1 EP 0006680 B1 EP0006680 B1 EP 0006680B1 EP 79300804 A EP79300804 A EP 79300804A EP 79300804 A EP79300804 A EP 79300804A EP 0006680 B1 EP0006680 B1 EP 0006680B1
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European Patent Office
Prior art keywords
gas
sulfur hexafluoride
mole
substantially uniform
dielectric
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EP79300804A
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German (de)
French (fr)
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EP0006680A1 (en
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Martin John Mastroianni
Sabatino Robert Orfeo
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Allied Corp
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Allied Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/16—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances gases

Definitions

  • Sulfur hexafluoride has found increasing use as a dielectric gas in high voltage electrical applications wherein the dielectric gas is subject to a substantially uniform electrical field.
  • Such applications include compressed gas insulated cables of the type used in power distribution substations for cables carrying high voltages, such as over 100 kilovolts.
  • the ratings of a cable of this type depends on a combination of the dielectric gas, the pressure to which the gas is subjected and the gap between conductors filled by the gas.
  • An improved dielectric gas would improve the rated voltage if the other factors were held constant or permit a relaxation of some other factor while retaining rated voltage.
  • the present invention is concerned with dielectric gases for a high voltage apparatus or device with a substantially uniform electrical field.
  • substantially uniform electrical field is meant a sphere to sphere, sphere to plane, or two coaxial cables or the like. Examples of such devices are short sections of bus and longer lengths of compressed gas insulated transmission systems rated between 145 to 800 kv, rms.

Description

    Background of the invention
  • Sulfur hexafluoride has found increasing use as a dielectric gas in high voltage electrical applications wherein the dielectric gas is subject to a substantially uniform electrical field. Such applications include compressed gas insulated cables of the type used in power distribution substations for cables carrying high voltages, such as over 100 kilovolts. The ratings of a cable of this type depends on a combination of the dielectric gas, the pressure to which the gas is subjected and the gap between conductors filled by the gas. An improved dielectric gas would improve the rated voltage if the other factors were held constant or permit a relaxation of some other factor while retaining rated voltage.
  • Many attempts have been made to formulate dielectric gases including gas mixtures of sulfur hexafluoride with improved electrical properties. Thus such mixtures have been discovered with improved dielectric strength in nonuniform fields or with dielectric strengths comparable to pure sulfur hexafluoride combined with improved other properties such as lowered dew points. Nevertheless other improved dielectric gases are still sought having such improved properties, especially for devices of the type wherein the gas is subjected to a substantially uniform field.
  • Sulfur hexafluoride has been tested for electrical and other applications in combination with noble gases and especially helium. In J. D. Cobine, Transactions Λ.l.E.E. vol. 74, part I, pages 318-321 (July 1955) mixtures of 40.2% and 80.6% sulfur hexafluoride and 59.8% and 19.4% helium had dielectric strengths less than pure sulfur hexafluoride in a test system having a sphere to sphere configuration.
    • Brief Description of the Invention
  • The invention includes an improvement in an electrical apparatus of the type having at least two electrical conductors separated by an insulative dielectric gas consisting essentially of sulfur hexafluoride and a noble gas subjected to a substantially uniform electrical field. In the improvement, the insulative gas consists essentially of 0.5 to 10 mole % of a noble gas preferably selected from the group consisting of helium, argon, krypton and neon, and 90 to 99.5 mole % of sulfur hexafluoride.
  • The subject dielectric gas mixtures have increased dielectric strength compared to pure sulfur hexafluoride and have potential advantages of lowered dew point and increased thermal conductivity.
    • Detailed Description of the Invention
  • The present invention is concerned with dielectric gases for a high voltage apparatus or device with a substantially uniform electrical field. By "substantially uniform electrical field" is meant a sphere to sphere, sphere to plane, or two coaxial cables or the like. Examples of such devices are short sections of bus and longer lengths of compressed gas insulated transmission systems rated between 145 to 800 kv, rms.
  • The present dielectric gas consists essentially of sulfur hexafluoride and a noble gas. The noble gas is 0.5 to 10 mole % of the mixture, with a preferred range being 1-10 mole % especially for lower pressure applications. In preferred devices, the dielectric gas is at a pressure between 15 and 100 psia (103 to 687 kPa). More preferred is 45-65 psia (310 to 450 kPa). Each of the noble gases, helium, neon, argon and krypton is found in some preferred gas mixtures, with the following examples showing synergistic breakdown voltages in uniform fields for helium, argon or krypton. Mixtures of noble gases are not excluded from the present invention, but they are generally not preferred.
  • The present dielectric gases may be used in the apparatus or device in the conventional manner now used for pure sulfur hexafluoride. The construction and introduction of such a gas into such devices are well known to the art and described, for example, in Compressed Gas Insulated Transmission Systems: The Present and Future, by A. H. Cookson of Westinghouse Electric Corp.
    • Example 1
  • Mixtures of sulfur hexafluoride and 1, 2, 3, 4, 6, 10, 20, 40 and 80 mole % helium were prepared and tested for breakdown voltage in a uniform field against pure sulfur hexafluoride and pure helium. The test cell included sphere to plane electrodes at 2.54 mm (0.1 inch) gap. Such tests were conducted at 15 psia (103 kPa), 30 psia (206 kPa) and 45 psia (310 kPa) which correspond to about 790, 1580, and 2370 millimeters of mercury absolute. In these tests, the gases were injected into an evacuated test cell to give the desired concentration and the voltage increased until breakdown occurred. The results at 30 psia are tabulated in Table 1, and the results at all three pressures are displayed in Figure 1.
    • Examples 2-3 and Comparative Examples 4-7
  • Example 1 was repeated, with fewer sampling points in some cases, with mixtures of sulfur hexafluoride and argon (Example 2), krypton (Example 3), hydrogen (Comparative Example 4), nitrogen (Comparative Example 5). CZF6 (Comparative Example 6) and CCL2F2 (Comparative Example 7). The results at 30 psia (206 kPa) are tabulated in Table 1, and, for examples 2 and 3, the results at all three pressures are displayed in Figures 2 and 3. None of the Comparative Examples show the marked synergism at about 80-99 mole % sulfur hexafluoride that is displayed by the noble gases in Examples 1-3.
    • Comparative Examples 8 and 9
  • Examples 1 and 2 were repeated for CF4 and 0, 1, 2, 3, 5, 10 and 20 mole % noble gas (helium in 8, argon in 9). As shown in Table 2, some synergism was shown compared to the base values for CF4, but the increase was much less than as shown for sulfur hexafluoride-noble gases in Table 1.
    Figure imgb0001
    Figure imgb0002

Claims (8)

1. A high voltage electrical apparatus having at least two electrical conductors separated by an insulative dielectric gas consisting essentially of sulfur hexafluoride and a noble gas and subjected to a substantially uniform electrical field, characterized in that the insulative gas consists essentially of 0.5 to 10 mole % of a noble gas and 90 to 99.5 mole % of sulfur hexafluoride.
2. An apparatus according to claim 1 wherein the insulative gas consists essentially of 1 to 10 mole 96 of said noble gas and 90 to 99 mole % of sulfurhexafluoride.
3. An apparatus according to either of claims 1 or 2 wherein said insulative gas is at a pressure between 310 and 450 kPa.
4. An apparatus according to any one of claims 1 to 3 wherein said noble gas is helium.
5. An apparatus according to any one of claims 1 to 3 wherein said noble gas is neon.
6. An apparatus according to any one of claims 1 to 3 wherein said noble gas is argon.
7. An apparatus according to any one of claims 1 to 3 wherein said noble gas is krypton.
8. An apparatus according to any one of claims 1 to 7 characterized in that the apparatus is a compressed gas insulated cable.
EP79300804A 1978-06-26 1979-05-10 Apparatus with dielectric gas mixtures in substantially uniform field Expired EP0006680B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US919338 1978-06-26
US05/919,338 US4204084A (en) 1978-06-26 1978-06-26 Apparatus with dielectric gas mixtures in substantially uniform field

Publications (2)

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EP0006680A1 EP0006680A1 (en) 1980-01-09
EP0006680B1 true EP0006680B1 (en) 1981-09-02

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US (1) US4204084A (en)
EP (1) EP0006680B1 (en)
JP (1) JPS554894A (en)
CA (1) CA1121008A (en)
DE (1) DE2960726D1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH664040A5 (en) * 1982-07-19 1988-01-29 Bbc Brown Boveri & Cie PRESSURE GAS-INSULATED CURRENT TRANSFORMER.
JPS60207300A (en) * 1984-03-30 1985-10-18 日本電子株式会社 Charged particle beam accelerator
JP2003286012A (en) * 2002-03-28 2003-10-07 Toshiba Corp Gas recycle system and method, gas insulation instrument, sulfur hexafluoride supply system and power industry system
US20070071047A1 (en) * 2005-09-29 2007-03-29 Cymer, Inc. 6K pulse repetition rate and above gas discharge laser system solid state pulse power system improvements
US7736529B2 (en) * 2007-10-12 2010-06-15 Honeywell International Inc Azeotrope-like compositions containing sulfur hexafluoride and uses thereof

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2757261A (en) * 1951-07-19 1956-07-31 Westinghouse Electric Corp Circuit interrupters
US2867679A (en) * 1952-12-04 1959-01-06 Gen Electric Gas composition for cooling and insulating purposes
US3059044A (en) * 1959-12-02 1962-10-16 Westinghouse Electric Corp Terminal-bushing constructions
US3249681A (en) * 1963-05-15 1966-05-03 Du Pont Self-extinguishment of corona discharge in electrical apparatus
GB1554424A (en) * 1975-06-23 1979-10-24 Allied Chem Composition and apparatus for suppresing carbon formation in electric discharges
US4110580A (en) * 1976-08-30 1978-08-29 Westinghouse Electric Corp. Gas-type circuit-interrupters having admixtures of helium with small concentrations of sulfur-hexafluoride (SF6) gas
US4190733A (en) * 1977-06-21 1980-02-26 Westinghouse Electric Corp. High-voltage electrical apparatus utilizing an insulating gas of sulfur hexafluoride and helium

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DE2960726D1 (en) 1981-11-26
US4204084A (en) 1980-05-20
EP0006680A1 (en) 1980-01-09
CA1121008A (en) 1982-03-30
JPS554894A (en) 1980-01-14

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